AAVSO Bulletin 76 for 2013 - How to Use the Bulletin

AAVSO Bulletin 76 - Predicted Dates of Maxima and Minima of Long Period Variables for 2013 - is published in the new format that was introduced in 2011. The information that was included in earlier numbers of the Bulletin is included in this new format, along with more information. The Bulletin does not include stars that do not have an AAVSO mean curve. Please read all of the materials provided to familiarize yourself with the new, customizable format of the Bulletin and all the ways you can use it in your variable star observing and research. If you have questions, please contact AAVSO Headquarters.

The AAVSO Bulletin is essential in planning your observing schedule each month. It contains predicted dates of maxima and minima of long period variables, and shows when a variable will be rising to maximum, fading from maximum, brighter than magnitude 11.0, and fainter than magnitude 13.5. The period covered is January 2013 through February 2014. You can access the Bulletin in the following ways:

The first step in planning your monthly observing schedule is to determine which part of the sky you will be able to see (see Table I below). Second, choose how you will look at the Bulletin according to the options above. Check the Bulletin file you have created or downloaded to find out which observable long period variable stars will be at the appropriate brightness for your equipment.

As an example, choose the schematic file (.pdf) of the entire sky for the entire 14 months the Bulletin covers. Table I below indicates that in the month of January, from 2 hours after sunset until midnight, stars between 1 hour and 9 hours of right ascension are observable. Look at the first page or two of the Bulletin .pdf to see a sample of the possibilities.

The word 'rising' means that the star is brightening towards maximum; 'fading' means it is fading from maximum. The number gives the approximate date on which the star should be at maximum or minimum.

If you have a 2.5-inch telescope which has a limiting magnitude of 10 to 11, the white boxes under January show that W CET, S SCL, S CET, T SCL, and several other stars will be brighter than magnitude 11.0 during this month and so they would be good candidates for observing with a small telescope.

With the same telescope, under January, the dark gray boxes show that S TUC, Y CEP, V AND, RR AND, and several other stars will be fainter than magnitude 13.5, and will be below the limit of a small telescope.

If you have a large-aperture telescope (6-inch or more) or a charge-coupled device (CCD), please observe faint magnitude stars, and in particular faint minima, since observers with smaller-aperture equipment can adequately cover the brighter stars.

A well-scheduled program making use of the AAVSO Bulletin will increase the value of your astronomical contribution, as well as heighten the efficiency and enjoyment of your observing.

TABLE I

Approximate Observing Windows Centered on the 15th of the Month from 2 Hours after Sunset to Midnight